Hydraulic transmission and differential gearing



July 4,1944. c. A. NORMAN 2,353,060

HYDRAULIC TRANSMISSION AND DIFFERENTIAL GEARING Filed Aug. 4, 1941 2 Sheets-Shea: 1

INVENT OR.

ATTQRNEYS l I July 4, 1944. c. A. NORMAN HYDRAULIC TRANSMISSION AND DIFFERENTIAL GEARING Filed Aug. 4, 1941 2 Theets-Sheet 2 INVENTOR.

ATTORNEY .5

,ment 4 in Fig. 1 may well resemble.

Patented July 4, 1944 nmmmr. GEABIN Carl- Norman, Columbus, Ohio Application August 4, .1941, Serial No. 405,421 H.

1 ellum; (01. 74-1395) Thisinvention relates to automatic speed changing and torque adjustment power transmission devices of the hydraulictype, particularly adapted to be embodied-in the driving axle of anautomotive vehicle to take the place of the angle gearing and differential gearing now commonlyemployed in such vehicles. 7

There are at the present time a great many hy- 1 draulic transmissions of turbo type, that is, comprising pump and turbine elements on the driving and driven shafts, respectively. provided with automatic torque and speed-adjustment for accommodating varying resistances on the driven shaft and varying power inputs on the driving shait. i

Almost in these transmissions is to utilize the residual velocity fromthe first turbine elementeither in successive turbine elements or in producing a head or an entrance velocity for the main pump element; Thepath'irom thezpump'elements to the turbine elements and back is made. as short as possible and usuallyappears in a section con-' universally the fundamental principle velocity from a turbine element mayyet represent'a comparatively insignificant energy loss.'

Thus a residual velocity of as-much as halt the entrance velocity would represent an energy loss of only per cent. It is therefore possible to'let the turbine-element rotate at a speed much be low that of most efllcient energy utilization and 1 yet secure a fair efllciency. For example, a speed reduction corresponding to thatof the second speed as compared with the direct drivein an ordinary passenger automobile would not mean a very great residual energy loss should an automatic turbo-transmission of anyone of most of the existing types be substituted forthe me- 'chanlcal reduction gearing now generally use The second 1 consideration "which has influenced the design herewith submitted is that,

- accordingto more recent investigations, in. great taining theaxis of rotation tobe approximately I ellipticalor circular. This is illustrated by the closed path formed by the es l--2-'-3-4-4 immediately adjoining the pump impeller on Figure 1 of the accompanying drawings. In a typical transmission device 01- this type, a stationary housing 2 adjoins the impeller and contains guide vanes I for discharging liquid on the turbine element 4. The liquid returns through the return passagel to the pump, inlet.

It should be noted, however, that while this path looks very smooth in the view presented, it

many impact and turbulence losses. due to theoretically incorrect exit and entrance angles may its own path of least resistance. Thus the clear.- ance between stationary element 3 and running large.

By observing these two considerations 9. simpliflcation of manyexisting designs is possible with a reduction in numbers oi stationary and running elements, and. it becomes possible to.

introduce combinations of functions in a way not formerly thoughtpo'ssible. Such a'combination is not nearly so smooth when viewed in the plane o! the bucket profiles, as'illustrated in Figures 3 and 4. The stationary guide vanes 3 may present a sharp turn in the path so as to make the liquid impinge on the turbine buckets 4 in the desired manner. a rule the vanes or buckets are curved not only in one plane, but in two or more, as illustrated by the buckets in an ordinary is herewith presented as my invention It combinesthe automatic turbo-transmission and the differential gearing into one unit.

The arrangement is shown in ,sectionalplan in Fig. 1, the section line being taken through the axis of the driving and driven elements, and in Francis turbine wheel, which the turbine elepartial vertical sectionto illustrate flow in Fig. 2, e

the section line being taken through the axis or the driving element at right angles to the driven element. A clarifying diagram of the blades and varies is given in Figure 3. Figure 4 illustrates a modification.

Referring to the form of invention shown in Figure 1, a pump impeller having radialfiow passages is mounted on the propeller shaft 5, which receives the drive from the engine. Suitable bearings are provided for mounting the propeller shaft in the main supporting housing. The impeller discharges liquid into the stationary housing 2 containing guide vanes 3. I These guide vanes are arranged on full circles with the intermediate axle shafts l as centers. The shafts I. These turbines drive the pump the housing tage aimed at by all positive drive differential gearing designs.

The means for reversing the direction of rota tion or the turbines are nt'anessential part of this invention, but are shown here merely to make clear that such reversal can easily be provided for. The means here suggested consist of an internal gear (see Fig. '1), which can slide axially. In the .positiomshown-,it ;ensages directly with apinion on the intermediate shaft I. To reverse, the internal gear' is shifted over toward the center of the device so as to engage full cylindrical discharge openings facing the turbine runners as in bine. The flow is in in Figure 2. It is proposed, for instance, that the left half of the pump circumference supplies the whole half of the pump circumference the whole right turbine. b--b is drawn the extreme far end :of the turbine housing,-and the flow line in the quadrantadjoining the top of-the impeller to the top vertical point on theturbine. larly, the return from the extreme far end of the turbine to the top of the mean inlet circle is illustrated by-fiow line a c-c, while thereturn from the top vertical point to anintermediate point on the. inlet circle is illustratedbythe flow line d-d.

an ordinary Francis turpart suggested by flow lines To illustrate this the flow line. from the top of the impeller toa-a from an intermediate. point Simia left turbine, and ,the wright To accomplish this the stationary "housing, as

shown in Figure 2, is shaped so as to merge'or pass over into a flat extension at the point I3.

and forks-into two branchesat-the point 14.:

The forked passage emerges at the points at the end farthest from the pumpin Figure .1. correspondingly, the now returns through forked passages II in Fig. 1 and over a central core 16, as shown also in Fig.2. Wideclearances I! are provided between the guide vanes 3-and running vanes 4, as illustrated in Figs. 3 and 4. to enable the device to operate more eiilciently at various speeds.

I'hedevice may be made to operate-as anautomatic transmission and a positive-drive 'dif-' ferential gear in the following manner: when it operates as a transmission, the right and left "pinion l2 driven by pinion I l on the intermediate only, itis-of course readily possible to arrange *While'I have here shown a single stage turbine two or more stages before discharge into passages 1 5.

The characteristic features of my invention include "'theiprovision in an automatically selfadiust'ing hydraulic nturb'o-differentijal searlng relying for efliciencyion 'ample clearancesbetween' stationary and running'elementsnot on-a multlplicity of stages oron the shortest possible circulatory path of carefully designed long-sweep passages, and 1 vane angles 1 adjusted-"to a certain dominating running: speed so that less common speeds above or belowxzthis dominatingspeed can be maintained without serious turbulence, im-

pact orresidualvelocity losses.

I claim as. my invention:

.A combined :aautomatic speed' changing, and

differential gearing of the flul'd pressure type comprising a driving element andtwo driven elements arranged symmetrically to the right and left of the: driving element and provided with fluidcirculatingchannels, and guide vanes turbines run at substantially thesame speed, the

"velocity and pressure head-delivered by the pump being converted into a torque reaction on the turbines. The greater the reduction, the slower the turbines run relatively to the impeller. This device,l however, also permits the two-wheel turblues to run atdifierent speeds as does anyfdifferential gear of the automobile driving axle type. In this case the greater hydraulic torque comes on the turbine that runs slower, that is, on the wheel that retains traction, while-a, slipping or racing wheel receivesa smaller torquethe faster it runs. This is, of course, theadvanfor the driven :elements arranged with their axes in parallel planes, the axis of'saiddrivlng' ele ment being :at "right angles to the axes of said driven elements; a Ic'asin'g fortsaid elements having: symmetrical 'nuid' :circulating channeIS provided with: guide vanes cooperating with said driven vanes'and dividedinto two systems disposedon opposite si'desrof a pl'anepassing through the axis of said :drivin'g element perpendicular to theaxis of said driven elementasaid guides being circumferential inextentspaced from said vanes to 'provide "wide' clearances therebetween, and :increase the efflciency' of operation under varyingspe'edratios thereof, a'power driven shaft for rotating said "driving "element, power distributing shafts operatively connected to said driven elements, respectively, said driven elements and power distributing shafts ibeing connected by speed -reduction1 and reversing gearing mounted in .said casingr and, means for shifting said' gearing from forward to backward direction andvice versa.. i

a 7 I flCARLA'NORMAN. 

